Currently, there is a great need for the development of new treatments that are effective against viral infections, particularly against viral infections which are associated with high morbidity and mortality, and which impact on sizable populations. Treatments currently available are inadequate or ineffective in large proportions of infected patients.
For example, in ameliorating AIDS symptoms and prolonging life expectancy, a measure of success has been achieved with drugs targeting the viral reverse transcriptase and protease enzymes (Miller and Sarver, 1997; Mitsuya, 1992; Moore, 1997; and Thomas and Brady, 1997). However, no single treatment method is completely effective against HIV infection. (Barry et al, 1998; Deeks, 1998; Miles, 1997; Miles, 1998; Moyle et al, 1998; Rachlis and Zarowny, 1998; Veil et al, 1997; Volberding and Deeks, 1998; and Volberdin, 1998).
PCT application PCT/AU99/00872 describes the use of compounds 5-(N,N-hexamethylene)-amiloride and 5-(N,N-dimethyl)-amiloride in the treatment of HIV infection.
Another virus considered to be a significant human pathogen is the Hepatitis C virus (HCV). This is a significant human pathogen in terms of both cost to human health and associated economic costs. HCV causes chronic hepatitis and cirrhosis and is the leading indicator for liver replacement surgery. In 2002 the Centre for Disease Control and Prevention estimated that more than 4 million people were infected in the USA alone and that approximately 8,000 to 10,000 die as a result of chronic HCV infection yearly. There is no known cure or vaccine. More effective pharmacological agents are urgently required.
A further well-known family of pathogenic viruses are the Coronaviruses. Coronaviruses (Order Nidovirales, family Coronaviridae, Genus Coronavirus) are enveloped positive-stranded RNA viruses that bud from the endoplasmic reticulum-Golgi intermediate compartment or the cis-Golgi network (Fischer, Stegen et al. 1998; Maeda, Maeda et al. 1999; Corse and Machamer 2000; Maeda, Repass et al. 2001; Kuo and Masters 2003)
Coronaviruses infect humans and animals and it is thought that there could be a coronavirus that infects every animal. The two human coronaviruses, 229E and OC43, are known to be the major causes of the common cold and can occasionally cause pneumonia in older adults, neonates, or immunocompromised patients (Peiris, Lai et al. 2003). Animal coronaviruses can cause respiratory, gastrointestinal, neurological, or hepatic diseases in their host (Peiris, Lai et al. 2003). Several animal coronavirus are significant veterinary pathogens (Rota, Oberste et al. 2003).
Severe acute respiratory syndrome (SARS) is caused by a newly identified virus. SARS is a respiratory illness that has recently been reported in Asia, North America, and Europe (Peiris, Lai et al. 2003). The causative agent of SARS was identified as a coronavirus. (Drosten, Gunther et al. 2003; Ksiazek, Erdman et al. 2003; Peiris, Lai et al. 2003). The World Health Organization reports that the cumulative number of reported probable cases of SARS from 1 Nov. 2002 to the 11 Jul. 2003 is 8,437 with 813 deaths, nearly a 10% death rate. It is believed that SARS will not be eradicated, but will cause seasonal epidemics like the cold or influenza viruses (Vogel 2003).
To improve the prospect of treating and preventing viral infections, there is an on-going need to identify molecules capable of inhibiting various aspects of the viral life cycle.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.